Erector sets, the ones with the brass nuts and bolts, the red tool kits, and the electric motors, head the list. Chemistry sets follow close behind. Those are the presents, say Fermilab physicists, that made their eyes light up on Christmas morning when they were children. Of course, in the case of the chemistry sets, it wasn't just their eyes that lit up. The explosive potential of the early product line of the A.C. Gilbert Company is legendary among Fermilab physicists, whose accounts of youthful chemistry experiments make the week after Christmas sound a lot like the Big Bang.

What are the other presents that physicists remember from Christmas past? CDF collaborator Brenna Flaugher had a set of wheels, curved tracks and straightaways that could be configured in three dimensions to send the wheels flying "off into the dining room."

Tom Diehl, of DZero, loved the model airplanes and boats that Santa brought when he was a lad. He put them together meticulously, he recalls, painting and finishing them with the utmost care ("good training for building wire chambers")--and promptly blew them up with the help of the faithful chemistry set.

Physicist Bill Foster enthusiastically described his Christmas joy, a "hydrodynamics kit," a set of plastic I beams, reservoirs, tubes, pumps and cups that could be put together in a refinery-like assembly that sent water flowing and flying in all directions. Microscopes were popular, and a primitive random-number generator called "electronic dice" fascinated the Beams Division's Paul Czarapata and his brother one Christmas.

Build-it-yourself crystal radio sets had a sizable following, initiating a new generation into the art of soldering. Various electrical kits made their appearance, although it was hard to compete with the electrical challenges associated with keeping strings of early Christmas lights aglow.

Then there were trains. Steve Holmes, who served as project manager for the Main Injector accelerator, remembers the Lionel train set that circled the family Christmas tree one year. Operating the train embodied many principles of physics, Holmes said, particularly after he reached the stage of making speeding locomotives collide. Could those boyhood hours around the tree have prefigured a lifetime's preoccupation with circular tracks, acceleration and collisions?

Physicist Steve Geer had a train set, too. Which he blew up. With gunpowder he made from his chemistry set.

Theorist Andreas Kronfeld liked Legos. Although his parents equipped him with the traditional Erector set, he found he lacked patience for tightening all the little bolts and nuts. Legos gave him the means to build fantastic constructions without the tedium of bolting them together. Perhaps it was at this point when Mrs. Kronfeld began to suspect she was raising a little theorist, not an experimentalist.

To hear physicists tell it, today's chemistry sets are pale imitations of the mayhem-in-a-box that they knew and loved; and the modern plastic incarnation of the Erector set would make A.C. Gilbert cringe. So what are physicists giving their kids this Christmas?

Little Alexander Kronfeld will be getting his first set of Legos. And Athena HaunParke, age 3, daughter of theorist Stephen Parke, will unwrap the gift that all the three-year-old girls are hoping for this year: her very own set of socket wrenches from Sears.

You never know: those Christmas Legos and wrenches could just be the inspiration for the next new generation of physicists.

"Hello Boys--
If you like thrills and adventure, you'll like being an Erector engineer."
(from an early Erector set manual)

In 1913, Alfred Carlton Gilbert developed the first Erector set, a boxful of girders, pulleys, gears, and the screws and tools to put them together. "From 1909 until his death in 1961," says the web site of the A.C. Gilbert Heritage Society, "[he] would revolutionize the toys that we would play with. For a little over 50 years, he brought us toys that made science fun."

After the Erector set came something called a physics set that never really caught on, a line of model trains, and the famous A.C. Gilbert chemistry set.

"In truth," the Gilbert site avers, "Mr. Gilbert meets the qualifications that place him among America's greatest men! Medical doctor, Olympic Gold Medal winner [for the pole vault in 1908], industrialist.... You name it.... What a record of accomplishments! His desire was not to accumulate great wealth, but to develop and market toys that would develop the engineers and scientists that our country must have if we are to maintain our position in the world."